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Voltage regulators hot

Old 09-02-2014, 05:02 PM
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Default Voltage regulators hot

I just replaced both Voltage Regulators on my carbed mercury 200XL.

I did not order the OEM, I got a generic mercury 6 wire, but it was listed as a replacement for a 854515 that was marked on the original. Just fired the boat up and to check and make sure it was charging. The battery was fully charged right at 12.9 volt so I wasn't noticing much extra voltage, but man the voltage regulators were getting really hot.

Is it normal for the VRs to get hot? I didn't have a thermometer, but I imagine they were hot enough to blister, while granted they didn't boil spit, they were still pretty hot.

Right now I have the lights on the boat to drain the battery down a bit then I was going to crank it back up and see if I could notice a greater difference.

The new VRs are basically identical in size, but the wiring was different. I had to cut both yellow wires and swap them over to the wiring harness from mine as well as one of the red wires on each vr. I looked at it pretty close and logically it would seem like the wiring should match, even though I did not have a wiring schematic to go by.

Thanks in advance
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Old 09-02-2014, 05:43 PM
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I kept looking around and found that 2 of the 3 fuses were blown under the flywheel. I'm hoping maybe these fuses are on the output side of the VR and they are converting all the extra voltage to heat.

That's sort of what they do from what I understand.
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Old 09-02-2014, 07:13 PM
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Voltage regulators do generate heat, and are typically heat sinked. Not to say everything is perfect in your setup , but I have my fingers crossed for you.
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Old 09-02-2014, 08:04 PM
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Check the bullet connectors to the regulator. They corrode and cause high resistance connections creating heat. I had one go up in flames on one of our boats at work. I also checked other engines and found the start of the same issues at the connectors on three engines. I cut the connectors out and hard wired them.

This was the one that caught fire.
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Old 09-03-2014, 07:44 AM
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well no dice. I picked up some fuses today and it blew them again. If I disconnect one of the red wires on my voltage regulator it will not blow the fuse. Not really knowing what the fuses actually go to, I'm not sure which way to proceed.

I hate to do it, but I might have to have a pro take a look.
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Old 09-03-2014, 08:51 AM
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Does your system look like the configuration shown below?

Have you checked the stator output voltages to verify they are within specification?

Make sure that the ground connection points (both of them) are clean and secure.

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Old 09-03-2014, 12:04 PM
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Jethro that looks pretty dang close. the only difference I see is my VRs are 6 wire, with a dedicated ground, where that one looks like it grounds through the body.

So if that's the case would it make any difference if you swapped up the reds? or the yellows? I'm not saying swapped a red for a yellow, but if you changed the positions of the yellows or if you changed the positions of the reds. It wouldn't seem like the reds would make a lick of difference.

So if what you are showing is what I have, the only thing that I can imagine would be popping my fuses would be if somehow the ere was a short letting the batter+ ground through the VR? or does that make sense?
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Old 09-03-2014, 12:06 PM
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I have not checked but I am guessing the fuses are inline with one of the reds. Would it not make sense to just run all the reds together?

Seems like it would do the same thing unless the wire is not heavy enough to hold all the current.
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Old 09-04-2014, 02:20 PM
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I am shaking my head. You have blown electronics on an alternator and now you want to short wires together and bypass fuses.
When it sends 30 volts to your electronics don't bother telling us - you will get a lot of crap over it .
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Old 09-04-2014, 07:33 PM
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Denny-O Why you mad bro? Aunt Flo come to visit?

Who said anything about blown electronics, alternators, shorting wires, or bypassing fuses?

FWIW I resolved the issue yesterday it turns out the VRs I had were shorted internally so one of the reds was effectively a ground. Found some used VRs at the boat yard and they worked as they should.

So Basically I appreciate everyone's comments, Jethro the wiring diagram explained a lot. Denny-O if its the thought that counts I appreciate the effort.
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